This invention relates generally to sample collectors, and in particular to a device for collecting animal and plant samples from water.
In most bodies of water such as rivers, streams, and lakes there is a wide variety of microscopic plants and animals in the water. In evaluating the health of a body of water, it is desirable to take samples of these microscopic plants and animals. For example, in assessing whether a body of water has been infested with zebra mussels, Dreissena polymorpha, a biologist takes samples of the microscopic community of the water to check for the presence of veligers and post-veligers, immature stages of the zebra mussel approximately 60 to 200 microns, whose presence indicates zebra mussel infestation. A preferred method of taking samples of post-veligers is to suspend glass slides in the water for a sufficient time for the plants and animals present to adhere to the slides. One side of the slide can then be cleaned, and the slide can be examined under a microscope to determine not only the types of plants and animals present, but their relative populations. While this procedure seems straight forward, there are difficulties in suspending the slides in the water. The slides should be held in a generally upright position, the surfaces generally parallel to the flow of water. The slides must be held securely and free from obstructions that would interfere with the deposit of plants and animals. Moreover, the slides must be secure whether the water is still or flowing. It is also important to be able to support the slides at various depths in the water column.
Another preferred method of taking samples of post-veligers, as well as veligers, is to suspend a polymer scrim or pad of polymer fibers in the water for a sufficient time for the plants and animals present to collect on or in the scrim or pad. The scrim or pad can be washed to remove any animals and plants that have collected in and on the fibers, and plants and animals that are removed can be examined under a microscope to determine not only the types of plants and animals collected, but their relative populations. While this procedure seems straight forward, there are difficulties in suspending the scrim or pad in the water. Like the slides, the scrim or pad should be held in a generally upright position, however the scrim or pad should extend transversely to the water flow, so that the water flows through the scrim or pad. The scrim or pad must be held securely and free from obstructions that would interfere with the flow of water over and through the scrim or pad, and the deposit of plants and animals thereon. Moreover, the scrim or pad must be secure whether the water is still or flowing. It is also important to be able to support the scrims or pads at various depths in the water column.
Slides are primarily effective for post-veligers, and provide quantitative data. A polymer scrim is effective for both veligers and post-veligers, but primarily provides qualitative data.
Generally, the sampler devices available are designed for the collection of periphyton. See, for example the sampler device shown in Doernberg et al., U.S. Pat. No. 3,955,421. These devices are submerged near the surface of the water, and hold a plurality of vertically oriented slides in a generally horizontal plane. These devices are not adapted for, and are generally unsuitable for, holding slides in the proper vertical orientation, parallel to the flow of the water, so that the water can flow unobstructed between the slides. Moreover, these device are generally too flimsy to support the slide at any appreciable depth below the surface, as is necessary for an accurate survey of certain plants and animals such as the zebra mussel. The currently available sampler devices tend to break apart and/or lose their slides under such conditions. Moreover, installing and removing the slides from such devices is difficult.